[HN Gopher] CoRncrete: A corn starch based building material
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CoRncrete: A corn starch based building material
Author : thunderbong
Score : 90 points
Date : 2024-10-05 18:51 UTC (4 hours ago)
(HTM) web link (research.tudelft.nl)
(TXT) w3m dump (research.tudelft.nl)
| thevtm wrote:
| This has been out for quite a while, there's even a YouTube video
| from 2015 showing how to make it using a microwave.
|
| https://www.youtube.com/watch?v=b7dYcJaCOMU
| acchow wrote:
| They mix 225g sand with 50g of corn starch.
|
| It's more "sand based" than "corn based".
| aaronblohowiak wrote:
| in concrete, cement makes up less than 25% of the mix, and
| here corn is like 20%, so I think when you're comparing this
| class of materials (concrete, epoxy granite, concrete), it
| makes sense to describe in terms of the binder even if it is
| a smaller % of the complete product.
| szvsw wrote:
| All concrete is more aggregate than binder... but it's the
| binder that matters from an emissions perspective.
| yunohn wrote:
| Well, tbf the paper clearly says it was published in 2017 and
| the first author is the same person who uploaded the presumably
| experimental stage video to YouTube in 2015.
| orbisvicis wrote:
| How does it handle water?
| kdtop wrote:
| Perhaps they have to seal it so water doesn't get in.
| hlieberman wrote:
| It's a concrete that: 1) breaks down in water in a day(!), and 2)
| has a "5 times higher impact on human health and 3 times higher
| impact on eco-toxicity as compared to concrete.".
|
| Cool research, but I'll pass on using it.
| klysm wrote:
| Having 'negative' results like this published is so good though
| because then it's harder to scam people with this idea in the
| future.
| mythas wrote:
| Yeah when the CORN-FREAKING-CRETE skyscraper crowd funding
| video comes out we can all be more skeptical than we were for
| SOLAR-FREAKING-ROADWAYS.
| szvsw wrote:
| Alternatively, some other researcher can say "cool, some
| problems I can try to address with future work!"
|
| Or it can go by the wayside. Both outcomes are fine. But no
| need to pre-emptively dismiss something that is obviously not
| being pitched as a production-ready building material...
| Animats wrote:
| This is much like staff.[1] Staff is a kind of cheap artificial
| stone, made from gypsum, cement, dextrin, and glycerin, with
| some long plant fibers for tensile strength. It was used for
| temporary exhibition buildings for various fairs a century ago.
| The Palace of Fine Arts colonnade in San Francisco, built for a
| 1915 fair, was originally made from staff. By the 1960s, it was
| a ruin. The current version is a full rebuild from 1974 in more
| durable materials.
|
| There are more promising bio-materials for construction.
|
| Attempts have been made to make boards from bagasse, the
| leftover fiber from sugar cane processing. It works, more or
| less. The most useful application for bagasse is making
| clamshell containers and plates for fast food. It's cheap,
| biodegradable, and non-toxic.
|
| [1] https://en.wikipedia.org/wiki/Staff_(building_material)
| yunohn wrote:
| Sometimes I wonder if buildings really should last hundreds
| of years taking up that space. Similar to how laws last
| almost forever and lead to byzantine requirements and tricky
| interpretations.
|
| Would be interesting if transient infrastructure and time-
| limited laws would lead to a more beneficial way of living.
| Cthulhu_ wrote:
| Japanese buildings are designed to last about 50 years
| iirc, after which they're demolished. Temples are rebuilt
| every X years as well. The building materials, at least in
| those temples, are mostly natural (wood, mostly cleverly
| jointed so minimal metal required). IDK if they're still
| popular but the tatami mat is made out of rice straw, also
| fully biodegradeable (assuming the stitching isn't
| plastic).
| theultdev wrote:
| Japan is not in the same era as what you're describing.
|
| There are many modern buildings that are built the same
| way as other modern cities and designed to last.
|
| They have very modern infrastructure, and while what
| you're describing does exist, but is by no means the norm
| nowadays.
| jedimastert wrote:
| The question then becomes how do you make a building
| degrade in a way that isn't dangerous to the occupants?
| When a building does degrade, it takes more energy to
| remove the debris and build a new structure. Can that be
| minimized as well? This isn't to say I'm against the idea,
| just thinking out loud
| yunohn wrote:
| I was thinking less about potential energy usage /
| emissions, so that's a good point. Probably solvable like
| the sibling comment about Japan.
|
| I was philosophizing more about changing the way we
| enforce permanency of decisions taken by humans who lived
| before on everyone who comes after them.
| Cthulhu_ wrote:
| They're building tall buildings out of "wood" nowadays, but
| it's so processed, sliced up, layered and laminated, and
| pumped full of epoxies that it's really more down to
| aesthetics than any environmental benefit; that is, effort /
| energy investment is high to the point where it's probably
| cheaper to make steel, and they're not biodegradeable.
| bobthepanda wrote:
| There's still some environmental benefit; wood is so much
| lighter than concrete or metal as a rule, that you end up
| needing not only less material in general but also less
| material in the structure because the frame weighs less and
| needs less support, not to mention general carbon savings
| from transportation of heavy material.
|
| It's also a major time saver since unlike concrete it
| doesn't need to set, and the products are basically
| manufactured panels that don't need specialized workers to
| install.
| skybrian wrote:
| That seems rather long-lasting for a temporary building. I
| wonder what other buildings should be temporary?
| Animats wrote:
| > That seems rather long-lasting for a temporary building.
|
| By 1964, not much of the colonnade was still standing. This
| was all that was left.[1] What you see today is a full
| rebuild.
|
| [1] https://www.sfgate.com/bayarea/article/Dramatic-Palace-
| of-Fi...
| szvsw wrote:
| Interesting. The degradation in wet conditions seems like a major
| challenge to solve.
|
| I initially was skeptical of the utility when I saw the mention
| of heating requirements, but the temperatures aren't that
| extreme, and seem very reasonably achieved with electrified
| energy sources (which in turn can easily be supplied via
| renewables).
|
| Being able to produce concrete without the emissions involved
| with the production of portland cement is a major goal of
| decarbonizing the building stock, so it's always good to see new
| lines of research in this front, even if still in the germinal
| stages!
|
| ARPA-E Hestia has some cool alternatives (a bit further along in
| research stages) for those interested:
|
| https://arpa-e.energy.gov/technologies/programs/hestia
| danans wrote:
| > Being able to produce concrete without the emissions involved
| with the production of portland cement is a major goal of
| decarbonizing the building stock
|
| AFAICT, cornstarch has a similar emissions to portland cement:
|
| https://apps.carboncloud.com/climatehub/product-reports/id/7...
| szvsw wrote:
| Yep, the authors do a relatively straightforward LCA and
| estimate essentially equally carbon footprint between
| concrete and "corncrete."
|
| Point still stands - it's a major goal of building technology
| to mitigate the embodied carbon of buildings due to concrete.
| danans wrote:
| A big possible issue with this is that cornstarch (at least the
| way it's currently produced) has the same carbon footprint as
| portland cement, which it replaces in this process.
|
| https://apps.carboncloud.com/climatehub/product-reports/id/7....
| szvsw wrote:
| The authors do mention approximately equivalent carbon
| footprints in their LCA, but they don't really explain how they
| account for the energy involved in heating the corncrete. If
| they are assuming a clean grid or renewable source already,
| then there's not much potential for reducing that carbon
| footprint. But if they are assuming a typical or dirty grid,
| then that's one area where the footprint can come down a
| significant amount. I was only skimming but I didn't see a
| mention of what assumption they used there.
| danans wrote:
| > But if they are assuming a typical or dirty grid, then
| that's one area where the footprint can come down a
| significant amount.
|
| Not sure I understand how, since regular concrete made from
| portland cement does require heating to cure - in fact it's
| exothermic.
|
| The vast majority of the emissions from traditional concrete
| come from the manufacturing of portland cement. It's not
| clear how a renewable grid would significantly lower the
| emissions of producing cornstarch, since the majority of
| emissions happen at the agricultural stage, via the petroleum
| based fertilizers.
| scythe wrote:
| Before you get too excited:
|
| - Global production of corn: 1.2 gigatonnes, source
| https://ipad.fas.usda.gov/cropexplorer/cropview/commodityVie...
|
| - Global production of Portland cement: 4.1 gigatonnes, source
| https://gccassociation.org/key-facts/
|
| And of course, cornstarch is only about 70% of the weight of
| corn. IIRC grain production statistics are usually by dry weight,
| but if we assume wet weight, it's even worse. Even if we
| completely obliterated the meat and biofuel industries worldwide,
| we would struggle to meet a quarter of the current demand for
| cement, which anyway is forecast to _increase_.
| dylan604 wrote:
| Here's hoping that corncrete doesn't interfere with all of that
| wonderful ethanol. /s
| photochemsyn wrote:
| Portland cement is not easily replaceable in its main use
| (building construction) because concrete made with organic
| substances as sand grain binders, be it cornstarch or epoxy-
| polymer, isn't fire resistant.
|
| The compressive strength of cornstarch concrete maxes out at 26
| MPa according to the paper, while different Portland cement
| formulations range from 20-50 MPa, and epoxy-polymer can go up to
| > 100 MPa, though brittleness is a problem.
|
| The optimal strategy for cleaning up Portland cement production
| is probably (1) renewable-based electrification of the kilns used
| to make CaO from CaCO3 (limestone), and (2) capture and
| stabilization of the CO2 from the kilns in a form like carbon
| fiber or diamond. Still a bit sci-fi but technologically feasible
| (but not economical at present).
| szvsw wrote:
| Another major area for decarbonization is also just better
| design - just by making it easier to fabricate and deploy
| shaped beams/floor systems which allocate material in a way
| that mildly follows the moment diagram, you can knock out
| massive amounts of emissions, just by virtue of the fact that
| the developing world will largely be building all floor systems
| out of concrete...
|
| https://doi.org/10.1016/j.engstruct.2021.112955
| notamy wrote:
| > Under water submerged conditions (20@C), hardened CoRncrete
| specimens showed partial to complete degradation within a day.
|
| While this certainly isn't great for most obvious building use-
| cases, I wonder if it would have utility for ex. building a
| research base on the moon someday.
| szvsw wrote:
| I actually have some friends working on construction materials
| for moon bases! ie turning regolith into bricks, using
| drones/robots to assemble the structures etc. pretty cool
| stuff. There's a fair bit of research going on into this
| problem.
|
| I think the main challenge with your idea is that you have to
| get the corn starch to the moon... you really want your
| solution to be focused on ISRU (in-situ research utilization)
| as much as possible.
| elif wrote:
| It's a 1:5 ratio starch:regolith
|
| I think you'll find that transporting the water is far more
| costly, which would be the case with any lunar concrete
| szvsw wrote:
| Makes sense!
| qup wrote:
| Do ants eat it? They eat some corn-based insulation I have.
| elif wrote:
| I'm gonna guess it's more likely that it won't last as a building
| material, rather than believe no one thought to mix sand,
| cornstarch and water until now..
| ncphil wrote:
| Encouraged to see the skepticism here.
|
| Recalling when, after years of hype, the demand for corn-based
| ethanol as a fuel competed with corn for food, leading to even
| greater food insecurity world-wide.
|
| Grifter's gotta grift, but that doesn't mean their BS gets to go
| unchallenged.
| metada5e wrote:
| Corn-based electrical insulators proved problematic in cars due
| to rodents eating the tasty insulators. Something to check in
| testing this material. Mycelium based construction materials may
| be more beneficial due to fire resistance, insulation and
| excellent R values and relative unpalatability. Ecovative is a
| good place to learn about this (no personal affiliations, just a
| fan.)
| bfung wrote:
| HN meta: an actual research paper vs product posing as science.
| Nice.
| voytec wrote:
| I love the name.
|
| EDIT: to make this comment a little less useless: here's Jonathan
| Davis performing for The Queen of the Damned movie. The official
| soundtrack release includes different performer's vocals. Davis
| had a contract at the time, which allowed him to sing for the
| movie, but not on the oficial OST release.
|
| https://www.youtube.com/watch?v=e_zySq3rxBU
| a1371 wrote:
| This is a thing not because it adds strength or sustainability.
| We produce way too much corn and they are looking for ways to use
| them up.
| jxf wrote:
| Unclear on that first point. The authors claim 26 MPa for
| CoRncrete, which is about the same as the higher end of the
| range of concrete (~28 MPa) but much cheaper. On the other
| hand, it sounds like the paper's saying it's also much less
| durable.
| LegitShady wrote:
| I wouldn't count anything under 40 MPA as "high strength
| concrete" at all. Thats where high strength concrete starts
| for me. High strength concrete mixes can go up to 180-200 MPA
| although thats some crazy specialty stuff for very niche
| uses.
|
| 25 mpa concrete is "i'm doing my driveway" concrete or "I
| bought a bag at home depot" concrete not high strength
| concrete.
| gigatexal wrote:
| Full article here:
| https://www.sciencedirect.com/science/article/abs/pii/S09500...
| major505 wrote:
| please, let it be the registed commertial name. I would be
| awsome.
| 29athrowaway wrote:
| Topsoil is very limited, this seems like a bad idea.
| otterley wrote:
| (2017)
| andai wrote:
| Does the polymerization prevent biodegradation (e.g. digestion by
| fungus)
|
| I don't think I have access to the full paper, but it is
| described as biodegradable, which seems to be the opposite of
| what you'd want your house to be made of?
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